Select: fix divider and focus issue

packages/select/src/option-group.vue

 <template>
-  <ul class="el-select-group__wrap">
-    <li class="el-select-group__title" v-show="visible">{{ label }}</li>
+  <ul class="el-select-group__wrap" v-show="visible">
+    <li class="el-select-group__title">{{ label }}</li>
     <li>
       <ul class="el-select-group">
         <slot></slot>

packages/select/src/select.vue

@@ -29,6 +29,7 @@
         :class="[selectSize ? `is-${ selectSize }` : '']"
         :disabled="disabled"
         @focus="handleFocus"
+        @click.stop
         @keyup="managePlaceholder"
         @keydown="resetInputState"
         @keydown.down.prevent="navigateOptions('next')"